Mini Redis

A Redis-like in-memory key-value store built from scratch in Rust. Built as part of a Rust learning journey — understanding how Redis works internally by implementing it.

What Is This

Redis is an in-memory key-value store used for caching, session storage, rate limiting, and job queues. It's fast because everything lives in RAM instead of disk.

This project implements a subset of Redis commands in Rust using a HashMap as the core data structure.

Architecture

mini_redis/
├── src/
│   ├── main.rs     → entry point + testing
│   └── store.rs    → core Redis store implementation
└── Cargo.toml

Data Types Supported

String  → SET name "Arjun"
Integer → SET counter 0 / INCR counter
List    → LPUSH / RPUSH / LRANGE

Commands Implemented

Core

Command	Description	Example
SET	Store a string value	SET name Arjun
GET	Retrieve a value	GET name
DEL	Delete a key	DEL name
EXISTS	Check if key exists	EXISTS name
KEYS	List all keys	KEYS
FLUSH	Clear everything	FLUSH

String

Command	Description	Example
APPEND	Append to string	APPEND name " Mehta"
STRLEN	Length of string	STRLEN name

Integer

Command	Description	Example
INCR	Increment by 1	INCR counter

List

Command	Description	Example
LPUSH	Push to front	LPUSH fruits apple
RPUSH	Push to back	RPUSH fruits banana
LRANGE	Get range	LRANGE fruits 0 2

How To Run

cargo run

Rust Concepts Used

• HashMap<String, RedisValue> — core data store
• Enum with data — RedisValue for multiple types
• Private fields + public methods — encapsulation
• Option<T> — safe key lookup
• Result<T,E> — error handling for type mismatches
• entry().or_insert() — default value pattern
• * dereference — modify values through references
• Module system — store.rs + main.rs

Roadmap

• REPL loop — type commands interactively
• Command parser — parse raw string input
• Error module — custom error types with thiserror
• More commands — DECR MSET MGET RENAME TYPE
• Hash type — HSET HGET HGETALL
• TTL — EXPIRE TTL PERSIST
• TCP server — real Redis protocol
• Persistence — save to file on exit